Hydraulic detent for valve



July 22, 1958 I J. H. EDMAN 2,844,1 6

HYDRAULIC DETENT FOR VALVE Original Filed Nov. 3, 1954 [N V EN TOR. J.h. E DMA/V United States Patent HYDRAULIC DETENT FOR VALVE John H.Edman, Waterloo, Iowa, assignor to Deere Mannfacturing Co., Dubuque,Iowa, a corporation of Iowa 4 Claims. c1. 137-622.5)

This invention relates to a fluid-pressure-operated dc tent for a fluidcontrol valve and more particularly to means for operating the detent byor in response to abnormal pressure in the circuit.

The application is a division of co-pending application Ser. No.466,649, filed November 3, 1954.

In a fluid-pressure-operated control system for agricultural implementsand other machines, it is customary to provide a valve shiftableselectively in opposite directions, for example, from a central neutralposition and to provide some form of means, customarily in the form of adetent, for retaining the valve in one or the other of its activepositions. It is also known to make provision for automatic return ofthe valve to its neutral position when the pressure in the system risesabove a predetermined value. One such example is disclosed in assigneesU. S. patent to Jirsa et al. 2,532,552. That design is typical of thoseusing mechanical means for returning the valve to neutral. According tothe present invention, the detent is released by at least a portion ofthe excess fluid pressure. It is a feature of the present invention toprovide first and second relief valves in series, the second valvehaving a setting lower than that of the first valve, together with meansincluding a detent-controlling passage connected to the relief conduitintermediate the relief valves and leading to a chamber for supplyingfluid under pressure to a piston associated with the detent. Theinvention features also means for locking out the detent when desired.

The foregoing and other important objects and desirable featuresinherent in and encompassed by the invention will become apparent as apreferred embodiment of the invention is disclosed, by way of example,in the following specification and accompanying sheet of drawings, theseveral figures of which are described immediately below.

Fig. 1 is a secitonal view through a representative valve housing.

Fig. 2 is a fragmentary sectional view as seen through the housing ofFig. 1 as cut by a plane including the line 22.

Fig. 3 is a fragmentary elevation as viewed in the direction of thearrows 33 in Fig. 2.

In the embodiment of the invention selected for purposes of the presentdisclosure, a main control valve housing has a vertical valve bore 12 inwhich is mounted an axially shiftable valve member 14 for selectivelysupplying fluid to one or the other of the opposite ends of a fluidmotor 16 of the cylinder and piston type, opposite ends of this motorbeing connected to the valve housing 10 by fluid lines 18 and 20, themotor and fluid lines 18 and 20 being illustrated schematically inconnection with the sectional remainder of the view.

The valve housing 10 has a high pressure passage 22 towhich fluid underpressure is supplied via a conduit 24 and any suitable pump (not shown).The conduit 22 branches at 26 and 28 to communicate respectively withupper and lower annular grooves 30 and 32, concentric in With the valvemember bore 12. The valve member 14 has a plurality of coaxially spacedapart lands or spools 34, 36, 38 and 40, separated respectively byintervening reduced portions 42, 44 and 46. These are instrumental incontrolling the circulation of fluid from the high pressure inlet 22selectively among the following grooves coaxially spaced apart along andconcentric with the valve bore 12: an upper motor groove 48, an upperreturn groove 50, and a lower return groove 52, the return grooves 50and 52 leading to a common return line 54. This line may lead to anysuitable reservoir (not shown) as contained within a casing 56, to therear wall 58 of which the valve housing 10 is connected.

The motor groove 48 leads via an upper check valve 60 to an upper motoroutlet which is in turn connected by a coupling 64 to the motor line 18.The lower motor groove 66 leads via a lower check valve 68 to a lowermotor outlet 70 which is in turn connected by a coupling or connector 72to the other motor line 20. When the valve member 14 is in its neutralposition as shown in Fig. 1, both check valves 60 and 68 are closed. The

lower branch 28 of the high pressure line 22 is connected 1 via 3246-52to the reservoir or return line 54. Hence, fluid circulates through thevalve structure at only slight pressure. When the valve member 14 isshifted upwardly, which may be accomplished by any suitable control suchas a housing-mounted rockshaft 74 and associated lever 76, the upperspool 34 on the valve member 17 exposes the upper high pressure branch26 to the upper motor groove 48 via the reduced portion 42 on the valve.At the same time, a ramp at the junction between the reduced valveportion 44 and its next adjacent spool 38 positively opens the lowercheck valve 68. The valve spool 40 cuts otf the communication betweenthe grooves 32 and 52, which leaves the high pressure line 2226connected solely to the upper motor groove 48 and fluid under pressureflows thence through the pressure-opened check valve 60 and line 18 tothe piston-rod end of the motor 16. Fluid returning from the oppositeend of the motor flows through the line 28, the coupling 72, the motoroutlet 70, past the positively opened check valve 68 and into the valvebore 12 between the valve spools 36 and 38. Since the valve member 14 isnow displaced upwardly, the upper reservoir groove 50 is exposed to thevalve bore and the returning fluid can flow to the common return line54. The other active position of the valve member is achieved when thevalve member is moved downwardly, in which case the motor line 20becomes the high pressure line and the motor line 18 becomes the lowpressure line, all of which is deemed to be clear from the foregoing andaccordingly further description is omitted.

The lower end of the valve member 14 is connected to centering means,here including a coiled compression spring 78 interposed between a pairof washers 80 and so arranged that regardless of the direction of axialmovement of the valve member 14, it will always be returned to itsneutral position as shown in Fig. 1. However, since it is desired tolock the valve member in one or the other of its active positions, thusrelieving the operator of the necessity of holding the valve, it isconventional to provide some form of detent means. In the present case,the detent means takes the form of a plunger 82 having its pointed endselectively engageable with either an upper groove 84 or a lower groove86 formed in the valve member 14 intermediate the centering springwasher 8t} and the spool 40; The plunger 82 has an intermediate pistonportion 88 and the plunger is spring-loaded by a coiled compressionspring 99, backed up by threaded plug 92, so as to be constantly urgedor biased toward engagement with the valve member 14. In the neutralposition of the valve member, the pointed end of the plunger 82 liesmidway between the upper and lower detent grooves 84 and 86. When thevalve member is moved downwardly to one of its active positions, thegroove 84 overrides the detent momentarily and the plunger seats in thegroove 84. The detent is releasable by manual force applied to the valvemember 14' to move it upwardly. The same relationship exists when thevalve member 14 is moved upwardly, except that the plunger 82 engagesthe lower groove 86.

The principal feature of the present invention is the provision of meansfor automatically releasing the detent action so that the operator neednot devote his attention to that task. In other words, the detent isreleased automatically in response to an abnormal increase in pressurein the circuit.

It will be understood from .the foregoing that there is a limited amountof axial movement of the valve member 14 in opposite directions withoutengaging the detent. That is to say, the distance between the grooves 84and 86, which constitute detent-receiving portions, permits this axialmovement and affords what may be termed slow-speed operation of thesystem. Of course,

as long as neither of the detent grooves is engaged, the

centering spring 78 will always return the valve member 14 to itsneutral or central position as soon as the operator relieves theapplication of force on the valve member control rockshaft 74.

The lower portion of the valve housing includes a relief conduit orpassage 94 which has its inlet end connected to an olfset portion 96 ofthe high pressure passage 2228. The passage 94 extends vertically aspart of or as including a lower counterbore 98, in which counterbore isprovided a relief valve spring 100 which acts against a relief valve inthe form of a ball 102 that seats against a seat insert 104 near the topof the passage. The vertical passage 94-104-98 is intersected by atransverse passage or conduit 106 (Fig. 2) which terminates at 108 in areturn or reservoir outlet. The junction between the conduit 106 and theoutlet 108 is in the form of a chamber 110 having a relief valve seat112 with which is cooperative a second relief valve ball 114. This ballis backed up by a coiled compression spring 116 which in turn is locatedby a threaded plug 118. A bleed 119 leads off from the passage 106upstream of the second relief valve ball 114, to prevent the entrapmentof fluid under pressure in the relief conduit.

The detent plunger piston 88 is contained and reciprocable in a plungercylinder or chamber .120, which is connected by angularly relatedpassage portions 122 and 124 with the relief valve passage 106, theconnection being made intermediate the relief valve balls 102 and 114.The end of the passage 124 is blinded at 126 against the rear wallportion 58 of the main case 56.

From the description thus far, it will be seen that an increase inpressure, above a predetermined value, in the circuit, will unseat thefirst relief valve ball 102, and a portion of this fluid will, via thepassage portions 124 and 122, enter the detent plunger chamber 120 aheador to the right of the plunger piston 88. Only a portion of the excessfluid is used, since the setting of the second relief valve 114 is lowerthan that of the first relief valve 102. In other words, the spring 100is stronger than the spring 116. Nevertheless, the fluid entering aheadof the detent piston 88 causes the piston 88 to move rearwardly againstthe bias of its spring 90, thereby withdrawing the pointed end of thedetent plunger 82 from whichever one of the detent grooves it isassociated with, whereupon the centering spring 78 automatically returnsthe valve member 14 to neutral. A bleed 128 leads off from the chamber120 behind the piston 88 and is directed to the centering spring chamberat 129, which chamber is connected to the reservoir in any suitablemanner (not shown). The purpose of the bleed 128 is to prevententrapment of fluid between 4 the threaded plug 92 and the back of thedetent plunger piston 88.

In a preferred form of the invention, the relief valves may beconsidered set, by way of example, in such manner that the first reliefvalve 102 will open at eleven hundred p. s. i. The second relief valve114 may be set to open at a pressure of one hundred p. s. i. The use ofonly a portion of the excess pressure to actuate the detent piston 88 ispreferable to subjecting the This means that the" pres piston to thefull pressure. sure on the detent means will always be uniform,consistent with the bias in the spring 116, the advantages of which willbe obvious without elaboration.

It is a significant feature of the present invention to provide meansfor selectively nullifying the effects of the detent means or piston andplunger 82-88. That portion of the valve housing 10 that forms thedetent chamber 120 serves as support means for a loclc elementdesignated generally by the numeral 130. This element comprises abi-positionable rockshaft 132 carried in a bore 134 that intersects thefront portion of the detent chamber 120. The inner end of the lockrockshaft 132 has means thereon in the form of an eccentric 136 whichengages the front face of the detent piston 88, that face of the pistonservin as a lock-receiving part for cooperation with the eccentric. Theexternal end of the rockshaft 132 has secured thereto means forselectively fixing the rockshaft in either one of two positionsangularly related about the rockshaft axis. This means comprises an arm138 having one end apertured at 140 to receive securing means, here inthe form of a cap screw 142. The external side of the valve housing hasa pair of spaced tapped bores, one of which coincides with the positionofthe cap screw 142 in Pig. 3 and the other of which is shown at 144- inFig. 3. When the arm 138 is in the position of Fig. 3, the cap screw14?. is passed through the arm aperture 140 and into the first mentionedaperture in the valve housing 10. The rockshaft is thus angularlypositioned in such manner that its eccentric 136 is in a forwardposition, which atfords maximum forward travel to the detent piston 88,and the detent means will function as described above for the purpose oflocking and releasing the valve member 14 under controlof pressure risein the system. However, when the cap screw 142 is removed and the arm isrotated to a position in which the arm aperture 140 is in register withthe valve housing tapped bore 144, the cap screw 142 can be passedthrough the arm aperture and threaded into the upper bore, the eccentric136 then moving rearwardly as the rockshaft is rocked and consequentlywithdrawing the pointed end of the detent plunger 82 from possibleengagement with either of the valve member grooves 84 or 86. Therefore,regardless of the extent of axial movement of the valve member, there isno detent means for locking the same in any of its active positions,with the 4 result that it will always be returned to neutral by actionof the centering spring 78 as soon as the operator relieves theapplication of manual force thereon.

In that form of the invention illustrated, the valve housing 10 is shownas one including a companion valve similar to the valve 14. The positionof this valve may be noted by the dotted'circle 146 in Fig. 2. A detentmeans similar to that described may or may not be used with the secondvalve, all of which is without significance here, reference being madeto the duplication of structure because of the disclosure thereof in theco-pending application of which the present application is a division.

The operation of the various components of the system has been describedin connection with the description of the structure. The overalloperational characteristics of the inventive design disclosed here canbe gathered from the functions ascribed thereto and accordingly need notbe elaborated. Features of the invention not categorically describedwill undoubtedly occur to those versed in the art, as will manymodifications and alterations'in the preferred embodiment of theinvention as presented here, all of which may be achieved withoutdeparting from the spirit and scope of the invention.

What is claimed is:

1. In a fiuid-pressure-operated control system: a valve housing havinginlet, motor and exhaust passages and a control valve movable from aneutral position to an active position and biased for return to saidneutral position for controlling said passages, said valve member havinga detent-receiving portion; means including a detent chamber having anopening leading to the detentreceiving portion of the valve member whenthe valve member is in its active position; detent means including apiston in the detent chamber having a detent element projecting throughthe opening for extension into engagement and retraction out ofengagement with the detentreceiving portion of the valve member;yielding means urging the piston in one direction to extend the detentelement for releasably locking the valve member in its active position;a relief conduit having inlet and exhaust ends connected respectively tothe inlet and exhaust passages and including a first relief valve biasedat a certain setting to close the relief conduit against inlet passagefluid pressure and yieldable to excess fluid pressure to open and enablefluid flow through the relief conduit to the exhaust end of saidconduit; a second relief valve in the'relief conduit downstream of thefirst relief valve and normally biased to conduit-closing positionagainst relief conduit fluid pressure and at a setting lower than thatof the first relief valve; and means including a detent passageconnected to the relief conduit intermediate the relief valves andleading to the detent chamber at the side of the piston in opposition tothe detent biasing means for supplying relief conduit fluid to thedetent chamber at a pressure in accord with the setting of the secondrelief valve to retract the detent element from engagement with thedetent-receiving portion of the control valve member so that said valvemember returns to neutral.

2. The invention defined in claim 1, including: support means comprisingpart of the detent chamber means; and a lock element carried by thesupport element for selective movement between a first position ofengagement with the detent means to retract the detent element fornullifying said detent means and a second position of disengagement fromthe detent means to enable normal functioning of the detent means.

3. In a fluid-pressure-operated control system: a valve housing havinginlet, motor and exhaust passages and a control valve movable from aneutral position to an active position and biased for return to saidneutral position for controlling said passages, said valve member havinga detent-receiving portion; a detent support adjacent to the valvemember and carrying a detent element for extension and retractionrespectively into and out of engagement with the detent-receivingportion of the actively positioned valve member, said detent elementhaving a lock-receiving part thereon; yielding means biasing the detentelement for extension thereof; and lock means for selectively nullifyingthe normal detent function of the detent element, including abi-positionable rockshaft on the support having an inner portioninteriorly of the detent support selectively engageable with thelockreceiving part of the detent element in one position of saidrockshaft to forcibly retract the detent element against engagement withthe valve member portion and in the other position to free said elementfor engagement with the valve member portion and further having an outerportion exteriorly of said support; and means for selectively fixing therockshaft in either position including an arm secured to and extendingradially from the outer portion of the rockshaft for rocking therockshaft between its two positions, and releasable fastener meanscooperative between the arm and the detent support for securing the armto the support in either position of the rockshaft.

4. The invention defined in claim 3, in which: the

free end of the arm is apertured, the support has a pair of openingsspaced angularly apart according to the two positions of the rockshaft,said openings and aperture being equidistant from the rockshaft axis,and said fastener means is received in the arm aperture and selectivelyreceivable in either support opening.

References Cited in the file of this patent UNITED STATES PATENTS2,276,979 Jacobi Mar. 17, 1942 2,545,573 Fletcher Mar. 20, 19512,617,626 Calkins Nov. 11, 1952 2,620,777 Towler Dec. 9, 1952 2,665,714Greenwood Jan. 12, 1954 2,689,585 Presnell Sept. 21, 1954

